The goal of this research is to improve the biocompatibility and performance of implantable microelectrodes for neurological sensing and stimulation. Neural electrodes are typically metallic devices that, while mechanically strong and highly conductive, do not always perform well in chronic implantation. The technical objective is to develop new designs and processing methods for applying electrically conductive silicone composite materials to implantable neuroprosthesis fabrication. Previously, we demonstrated the feasibility of synthesizing polymer nanocomposites having the elasticity of silicones and near-metallic electrical conductivity. Simple single-pole, polymer-based prototypes were found to be stable toward simulated physiological conditions and cyclic current pulsing. The proposed study would extend this technology to the fabrication of more complex and miniaturized devices including multi- poled cuff electrodes. Cuff electrodes are cylindrical devices, specifically designed for fitting- around individual peripheral nerve endings. The test plan would include developing advanced fabrication methods and testing the prototype neuroprostheses for electrical response, compatibility, and durability in chronic implantation applications. If successful, this research will produce implantable neural devices with significantly greater biocompatibility than the present technology. The broader impact to society of this new technology would be more effective treatments for neurological disorders including Parkinson's disease, epilepsy, deafness, stroke, and paralysis. [unreadable] [unreadable] [unreadable]